For example, while the RL95-2 and ECC-1 cell lines are both considered receptive and both express estrogen and progesterone receptors (96, 97), their cellular makeup is likely still different because they a derived from endometrial adenosquamous carcinoma and endometrial adenocarcinoma, respectively (96, 97). Here, PGR is linked to endometrial adenosquamous carcinoma.